In recent years, liquid crystal display devices are widely used as display devices for monitors, projectors, mobile information terminals, mobile phones, and the like. Generally speaking, a liquid crystal display device allows the transmittance (or reflectance) of a liquid crystal display panel to vary with a driving signal, thus modulating the intensity of light from a light source for irradiating the liquid crystal display panel, whereby images and text characters are displayed. Liquid crystal display devices include direct-viewing type display devices in which images or the like that are displayed on the liquid crystal display panel are directly viewed, projection-type display devices (projectors) in which images or the like that are displayed on the display panel are projected onto a screen through a projection lens in an enlarged size, and so on.
By applying a driving voltage which corresponds to an image signal to each of the pixels that are in a regular matrix arrangement, a liquid crystal display device causes a change in the optical characteristics of a liquid crystal layer in each pixel, and regulates the transmitted light using optical elements disposed on the front and rear sides of the liquid crystal layer, such as polarizers, thereby displaying images, text characters, and the like. In the case of a direct-viewing type liquid crystal display device, the optical elements are usually attached respectively to a light-entering substrate (the rear substrate) which is provided on the backlight side of the liquid crystal display panel and a light-outgoing substrate (the front substrate or viewer-side substrate).
Methods for applying an independent driving voltage for each pixel include a passive matrix type and an active matrix type. Among these, on a liquid crystal panel of the active matrix type, switching elements and wiring lines for supplying driving voltages to the pixel electrodes need to be provided. As switching elements, non-linear 2-terminal devices such as MIM (metal-insulator-metal) devices and 3-terminal devices such as TFT (thin film transistor) devices are in use.
Liquid crystal display devices are also used as display devices for use in onboard devices, such as car navigation devices, instrument panels, etc., as well as television sets, personal computers, and mobile phones. In onboard applications, for safety and other reasons, display devices are required to produce no reflection of images on the windshield.
With the view of meeting such a requirement, Patent Document 1 describes the technique of restricting visible angles of images by means of a louver film which is attached as a light control film to an onboard display device.
Patent Document 2 describes a liquid crystal display device in which, with the view of improving the light utilization efficiency of the liquid crystal display device, microlenses are provided over a liquid crystal display panel for collecting light onto corresponding pixels, whereby the effective aperture ratio of the liquid crystal display panel is improved.
Patent Document 3 describes a method of forming such microlenses with high accuracy. The microlenses of Patent Document 3 are formed by irradiating a photocurable resin applied over a substrate with light incoming from a color filter substrate side via pixel apertures and thereafter performing photolithography processes including development, heating, etc. The irradiation step employs a so-called self-alignment exposure method in which the incidence angle of light transmitted through the pixel apertures is changed during exposure. This exposure method enables microlenses to be formed so as to correspond to respective pixels in a self-aligning fashion (formation of microlenses by a self-alignment method) and therefore does not require alignment of a mask for forming microlenses. Thus, the pixel apertures and the microlens array can be aligned with extremely high accuracy.    Patent Document 1: Japanese Laid-Open Utility Model Publication No. 2-117585    Patent Document 2: Japanese Laid-Open Patent Publication No. 11-194332    Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-196139 (Japanese Patent No. 3708112)